The present invention addresses the problem of formulating sulphonylureas for agrochemical use, alone or combined, such that both the packaged formulation, the emulsion made by the farmer and the active ingredient(s) (Als) are stable and maintain a suitable biological activity.
Mixtures of sulphonylureas with other active ingredients for broad-spectrum formulations, non-exclusively including herbicides, fungicides, insecticides and plant hormones are also contemplated.
The solution proposed in this invention is the formulation of said sulphonylureas (SU) (optionally with other Als) with certain coformulants (formulation ingredients other than the Al) in certain proportions, the combination of the base oil (solvent) with a derivative of organic silane of the commercial type Break Thru® (trisiloxane polyethers) being essential.
There are several problems associated with oil formulations of herbicides, the detection and characterization of which has been an essential part of the research carried out in order to overcome them, and which is therefore considered as part of the inventive step of this patent.
Among the problems found we can highlight:
i) During and after the grinding process, the sulphonylurea crystals tend to aggregate
ii) The use of oils in which sulphonylurea solubility is “relatively high” creates problems regarding biological activity, since part of the Al is in crystal form when applied; and part is dissolved in the base oil, specifically in those oils with low boiling points universal solubilising agents (for example, cyclohexanone).
iii) The stability of oil suspensions in the state of the art can be improved upon-since the usual viscosity modifiers in agrochemical formulations do not have the desired effect
iv) Biological activity is very related (especially with sulphonylureas) with the formulation's wetting ability
v) Al stability is very dependent on the medium (oil and coformulants)
vi) product homogeneity tends to be very low, with short-term phase separation
Sulphonylureas are highly active herbicides with low toxicity.
It is understood that throughout this patent, the term sulphonylureas also includes the so-called sulphonamides. These two terms are occasionally used interchangeably or even confused: we would like to note that we always refer to both types with the term “sulphonylureas”.
Non-restrictive examples of sulphonylureas object of the invention, are: amidosulfuron, azimsulfuron, bensulforon, chlorimuron, chlorsulfuron, cinosulfuron, cyclosulfamuron, ethametsulfuron, ethoxysulfuron, flazasulfuron, flupyrsulfuron, foramulfuron, halosulfuron, imazosulfuron, iodosulfuron, mesosulfuron, nicosulfuron, oxasulfuron, primisulfuron, prosulfuron, pyrazosulfuron, rimsulfuron, sulfometuron, sulfosulfuron, thifensulfuron, triasulfuron, tribenuron, trifloxysulfuron, triflusulfuron, tritosulfuron; as well as active herbicide derivatives (such as methyl, ethyl or alkyl ethers or esters) and salts thereof.
They are easily degradable, especially in aqueous mediums.
It is known that SUs can be formulated in oil medium in order to improve their stability.
Since it is a very important requirement of the agrochemical sector, there are numerous patents and articles relating to the same problem indicated in this invention, but they solve it by other means.
Some documents demonstrate that their formulation as oil suspensions improves SU stability, particularly when used in combination with urea. However, the stability of said formulations is far from optimal.
Our formulations, even without urea, show adequate stability. None of the tests performed with different products in the market have provided any formulation as stable as those proposed (e.g. Examples 1, A and B) since, despite the fact that adequate product stability and homogeneity can be obtained in laboratory conditions and with skilled handling, it is true that the products mentioned must be handled, amongst others, by farmers in their own facilities, and real usage conditions may therefore be very different from the conditions in which the laboratory tests were performed, causing a great reduction in product stability/homogeneity, and therefore a great reduction in product qualities: this relates essentially to the need of strong stirring and the necessary industrial application of the formulation (i.e. coformulant availability at the industrial level, their price realistically allowing industrial use).
Take as an example the photograph in FIG. 1, that shows a sample of the leading formulation of sulphonylurea nicosulfuron that in the market Motivell® (BASF), where there is an evident separation of the phases when left to settle for some days (15 days at room temperature and 8 at 54° C.).
Errors and omissions excepted, neither the applicant or the inventors know any commercially viable product that offers a stability such as the one proposed, neither, in fact, have they found anything at the commercial level or published in scientific articles or registered with stability characteristics such as those obtained by the product object of the present invention.
Some patents that describe-different solutions toe the aforementioned problem are:
WO2007/042152 (Vermeer et al., Bayer), wherein an SU is combined with pyrethroids, with the use of cyclohexanone (which is very inflammable and is not used in this invention).
DE10258216 (anonymous, Bayer), wherein a sulphosuccinate is necessarily used (we do not use sulphosuccinates in our invention).
US2006/0276337 (Sterne et al, Bayer) where it is shown in [0415] that the preferred embodiment required the use of a sulphosuccinate, as demonstrated in the examples and deduced from the description (we do not use sulphosuccinates in our invention).
WO2007/028517 (Bailo-Schleier-Macher et al., Bayer) where an oil suspension is used to fight against the eggs and nymphs of the white fly, being applicable only in neonicotinoids (not sulphonylureas)
WO2007/042138 (Schnable et al., Bayer) where polycation salts of certain solubility in water are used (not used in our invention)
EP554015 (Kanbayashi et al., ISK), where the use of sulphonylureas in oil suspensions is protected when combining an emulsifier, an oil and urea.
There are other patents dealing essentially with the type of oil used in the suspension, but none of them shows the preferred use of a paraffin oil with an organomodified silane derivative. For a better embodiment, we recommend the preferred use only of paraffin oils—or at least mixtures containing at least 10% of these—, since these paraffin oils in combination with the organomodified silane derivatives show greater stability than the rest when used according to our invention.